南极大型海藻表面可培养琼胶降解菌多样性分析

BIODIVERSITY ANALYSIS OF CULTURED AGAR-DEGRADING BACTERIA FROM SURFACES OF ANTARCTIC MACROALGAE

采用选择性培养基、卢戈氏染色法对南极乔治王岛附近海域6株大型海藻表面可培养的琼胶降解菌进行了筛选和分离纯化,并基于菌株的16S rRNA基因序列进行了分子鉴定和系统发育分析。结果表明,筛选获得的37株琼胶降解菌分别属于γ-变形菌纲(Gammaproteobacteria),黄杆菌纲(Flavobacteriia)和放线菌纲(Actinobacteria)。其中γ-变形菌纲包括Pseudoalteromonas、Colwellia、Shewanella、Psychrobacter、Pseudomonas、Halomonas、Photobacterium等7个属及Thiotrichaceae科,黄杆菌纲包括Flavobacterium、Zobellia 2个属,放线菌纲只筛选出Salinibacterium 1个属。优势属为假交替单胞菌属(Pseudoalteromonas,20株),其次为嗜冷杆菌属(Psychrobacter,4株)。Shewanella、Psychrobacter、Pseudomonas、Halomonas和Photobacterium等5个属及Thiotrichaceae科是首次从南极大型海藻表面分离的具有琼胶降解活性的种属。该结果拓展了我们对琼胶降解菌多样性的认识,为南极微生物资源调查和开发研究提供了科学依据。

To analyze the diversity of cultured agar-degrading bacteria from the surfaces of six Antarctic macroalgae samples collected from King George Island,a selective medium and Lugol’s iodine staining method were used to screen and purify the agar-degrading bacteria,and the phylogenetic relationships of these strains were then investigated according to their 16S rRNA sequences.Thirty-seven strains of agar-degrading bacteria were screened,purified,and identified as belonging to the Gammaproteobacteria,Flavobacteriia,and Actinobacteria,respectively.At the genus level,the strains were classified as Pseudoalteromonas,Colwellia,Shewanella,Psychrobacter,Pseudomonas,Halomonas,Photobacterium,Flavobacterium,Zobellia,and Salinibacterium,in addition to a strain that was classified as belonging to the family Thiotrichaceae.Among them,Flavobacterium and Zobellia belong to the Flavobacteriia,Salinibacterium belongs to the Actinobacteria,and the remaining genera belong to the Gammaproteobacteria.The most dominant genus of agar-degrading bacteria was Pseudoalteromonas(20/37),followed by Psychrobacter(4/37).Shewanella,Psychrobacter,Pseudomonas,Halomonas,Photobacterium,and the member of the family Thiotrichaceaeare the first reported taxa with agar-degrading activity isolated from the surfaces of macroalgae in Antarctica.The results not only expand our knowledge of the diversity of agar-degrading bacteria,but also contribute to the investigation and exploitation of Antarctic microbial resources.